LeetCode36.有效的数独 JavaScript

判断一个9x9的数独是否有效。只须要根据如下规则,验证已经填入的数字是否有效便可。javascript

  • 数字1-9在每一行只能出现一次。
  • 数字1-9在每一列只能出现一次。
  • 数字 1-9在每个以粗实线分隔的 3x3 宫内只能出现一次。

上图是一个部分填充的有效的数独。java

数独部分空格内已填入了数字,空白格用 '.' 表示。ui

示例 1: 输入:spa

[
  ["5","3",".",".","7",".",".",".","."],
  ["6",".",".","1","9","5",".",".","."],
  [".","9","8",".",".",".",".","6","."],
  ["8",".",".",".","6",".",".",".","3"],
  ["4",".",".","8",".","3",".",".","1"],
  ["7",".",".",".","2",".",".",".","6"],
  [".","6",".",".",".",".","2","8","."],
  [".",".",".","4","1","9",".",".","5"],
  [".",".",".",".","8",".",".","7","9"]
]
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输出: truecode

示例 2: 输入:cdn

[
  ["8","3",".",".","7",".",".",".","."],
  ["6",".",".","1","9","5",".",".","."],
  [".","9","8",".",".",".",".","6","."],
  ["8",".",".",".","6",".",".",".","3"],
  ["4",".",".","8",".","3",".",".","1"],
  ["7",".",".",".","2",".",".",".","6"],
  [".","6",".",".",".",".","2","8","."],
  [".",".",".","4","1","9",".",".","5"],
  [".",".",".",".","8",".",".","7","9"]
]
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输出: false 解释: 除了第一行的第一个数字从5改成 8 之外,空格内其余数字均与 示例1 相同。 但因为位于左上角的3x3 宫内有两个 8 存在, 所以这个数独是无效的。blog

说明: 一个有效的数独(部分已被填充)不必定是可解的。 只须要根据以上规则,验证已经填入的数字是否有效便可。 给定数独序列只包含数字1-9和字符 '.' 。 给定数独永远是 9x9形式的。ip

答案参考:string

/** * @param {character[][]} board * @return {boolean} */

var isValidSudoku = function(board) {
// 检查每一行
  for (let arr of board) {            
    let row = []
    for (let c of arr) {
      if (c !== '.') row.push(c);
    }
    let set = new Set(row)
    if (set.size !== row.length) return false;
  }
  
// 检查每一列
  for (let i = 0; i < 9; i++) {
    let col = []
    board.map( arr => {
      if (arr[i] !== '.') col.push(arr[i])
    })
    let set = new Set(col)
    if (set.size !== col.length) return false;
  }
  
// 检查每一个小方块
  for (let x = 0; x < 9; x += 3) {
    for (let y = 0; y < 9; y += 3) {
      let box = []
      for (let a = x; a < 3 + x; a ++) {
        for (let b = y; b < 3 + y; b ++) {
          if (board[a][b] !== '.') box.push(board[a][b])
        }
      }
      let set = new Set(box)
      if (set.size !== box.length) return false
    }
  }
  
  return true
};
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